Solution concentration system



D- 8,1942- R. B. P. RAwFoRD 2,304,150`

SOLUTION COCENTR'I:[ON` SYSTEM I I Filed May 15,1938 2 sheets-sheen 18s' 86 sa Inventor Gttorneg De@ 8, l942 R. B. P.- CRAWFORD SOLUTIONCONCENTRATION ASYSTEM Filed May l5, 1938 2 Sheets-Sheet 2 ma@ i:inventor Ittomeg Patented Dec. 8, 1942 UNITED STATES "PATENT OFFICE2,304,150 Y l f t f SONTTEM `13 IClaims.

This invention relatesto solution concentrating systems for chemicaldehumidifying systems in general and more particularly to an automaticcontrol system therefor to insure safe operation thereof.

The chemical dehumidifying system of this invention may utilize ahygroscopic fluid such as calcium chloride, lithium chloride or anyother chemical having moisture absorbing characteristics and it maycomprise a boiler for heating the hygroscopic uid to increase theconcen' tration thereof, a first conduit for conducting hygroscopicfluid of relatively high concentration from the boiler to adehumidifying unit provided with means for contacting the hygroscopicuid with the air to be dehumidied, a second conduit for conductinghygroscopic uid of relatively low concentration from the dehumidifyingunit to a reservoir and a third conduit for conducting the fluid fromthe reservoir to the boiler;

An object of this invention is `to provide a means for obtainingcounteriowheat exchange between the hygroscopic uid flowing through thefirst and second conduitswhereby the efficiency of the system is greatlyincreased.

Another object is to provide heating means in the first conduit toprevent solidiiication of the uid of relatively high concentrationflowing through the rst conduit,

A further object is to provide means for maintaining at least apredetermined amount of uid in the,l reservoir so that the boiler may beat all times supplied with fluid.

Still another object is Vto provide means for decreasing the flow offluid to ythe rreservoir if the level of fluid therein becomesexcessively high. f

A further object is to provide means for maintaining the temperature ofthe fluid in the boiler at a substantially constant value by controllingthe firing means of the boiler.

Another object is to cause agitation of the fluid in the boiler incaseit tends to stratify. This maybe accomplished by controlling theagitation of the uid in accordance with the difference in temperature ofthe iiuid at diierent points Within the boiler.

Another object is to maintain the level of the fluid in the boiler at asubstantially constant value by controlling the flow of iiuid from thereservoir to the boiler.

Still another object is to shut off the firing means for the boiler andsupply uid to the reservoir andhenceto the boiler if the fluid `1eve1inthe boter shou1d decrease to :1t-.predeter-v mined low value. y y

A further object is to supply air under pressurey to prevent, excessiveturbulence of .the'fluidu iny the boiler. v

'Ihis invention also contemplates the combination of these variousfeatures into a composite control `arrangement to insure safe operationof a Vchemical dehumidifying system.

Other objects and advantages will become apparent to those skilled intheV art upon reference to the accompanying specification,v claims anddrawings, in which Figure 1 is a diagrammatic illustration -of this.

invention with the control system applied there-v Figure 2 is aschematic Wiring diagram showing schematically .the construction. ofthev various control instrumentsand the wiring connec- A is containedthe hyg'roscopic fluid to be concen-v trated, and a firing chamber I2vfor heating the hygroscopic uid in the shell II. The boiler may befired-by means of la burner, such as a high-low oil burner. I3. Gases'of combustion are withdrawn fromjthe boiler I0 by means of a flue orbreech I4 extending to a stack, not shown.

' Fuel such as oil may be supplied to the burnerv I3 through' a pipe I5under the control of a mo'- jtorized main valve IB. A branch pipe I'Iextend ing to thev burner I3 is controlled by a manually adjustedthrottle valver I8 and a branch pipe Il extending to the burner I3 maybe controlled by a motorized valve 20. When the motorized main valve I6is open, fuel is supplied to the burner I3 yand if the motorized valve20 is closed the fuel passes through the manual valve I8 to provide alow ame, and if the motorized valve 20 is open, a high ame is provided.

Hygroscopic iluid of arelatively high concenfV tration, for example 50%,is Withdrawn from the shell II by a pump 23 through a conduit 22, aheatexchanger 24, a conduit 25, a cooler 26 andaconduit 21 toa sump 28 of adehumidifying unit generally designated at 29. Preferably the pump 23 ismaintained continuously in oper-l ation. ,The cooler 26 may be providedwith an inlet 30 and an outlet 3l for a cooling fluid such as.Well-Water for cooling the hygroscopic uid beforeit passes to the sump28 of the dehumidifying unit 29. Abranch conduit 25' may be utilized forsupplying. hygroscopic fluid to other .a concentrator in dehumidifyingunits, not shown. A motorized valve 32 located in the conduit 21 may beutilized for controlling the supply of concentrated fluid to thedehumidifying unit.

The dehumidifying unit 29 may comprise a chamber 33 provided with an airinlet 34 and an air outlet 35. Air is drawn through the chamber 33 bymeans of a fan 36 and discharged by a conduit 31 to the space .or roomto be conditioned. Located in the chamber 33 is a cooling coil 38 forcooling the air .passing through the chamber. This cooling coil may beprovided with a cooling fluid in any suitable manner.

pump 39 withdraws hydroscopic fluid from the .I

sump 28 through a conduit 49 and discharges this hygroscopic fluidthrough a spray 4I so that the hygroscopic fluid is contacted by the airpassing through the dehumidifying unit toabsorb moisture therefrom. As aresult, the confy centration of the hygroscopic fluid is decreased to apredetermined low value such as 45%.

' This hygroscopic fluid of relatively low concentration passes from thesump 28 through an overflow connection 43, a conduit v44, the heatexchanger 24 and a conduit 43 to a vreservoir generally designated at41.V

The temperature of the hygroscopic fluid of relatively highconcentration passing through the conduit 22 from the boiler isrelatively high and it is necessary that this temperature be reducedbefore the highly concentrated hygroscopic fluid is supplied to thedehumidifying unit 29. Also, the temperature of the less concentratedhygroscopic fluid returning from the de. humidifying unit 29 is ofrelatively low temperature and must be heated in the boiler Ill to driveoff the moisture contained therein. The heat exchanger 24 causescounterflow heat exchange between the hygroscopic fluid of relativelyhigh concentration and the hygroscopic uid of relatively lowconcentration, whereby the overall efficiency' of the system isincreased.

The reservoir 41 may comprise a container 49 in which the hygroscopicfluid may be stored pref paratory to being supplied to the boiler I6.The container 49 is provided with a duct 5U leading to the breech I4.The container 49 is provided with an overflow passage 5I which emptiesinto a sewer 52. It is possible that under certain eX- treme conditionssuch as failure of the controls, the reservoir 41 may become filled withhygroscopic fluid to an overflow point. and-instead of permitting thisfluid from'passing out through the flue or breachjit is made to pass outthrough the overflow conduit 5I. Under these conditions suitablereceptacles such as barrels or tanks 53 may be utilized for catchingthis overflow of hygroscopic fluid so that it willnot be Wasted.

A conduit 55 extending from the reservoir 41 to the shell I I of theboiler I0 supplies hygroscopic fluid from the reservoir 41 to the shellII. The supply of fluid is controlled by a motorized valve 56 and if thelevel of the reservoir 41 with respect to the boiler I0 is such thatgravity flow is not sufficient for this purpose a pump 51 may beutilized.

A conduit 59 connected between the conduit 22 and the reservoir 41 maybe utilized undercertain conditions for supplying highly concentratedfluid from the boiler I0 to the reservoir 41. This conduit 59 iscontrolled by a motorized valve 60. A conduit 6I extends between theboiler shell II and the reservoir 41 so that the steam and entrainedfluid escaping from the boiler will pass through this conduit 6I intothe reservoir 41 and the moisture will pass through the passage 59 intothe breech or flue I4. The conduit 6I also serves to equalize thepressures between the boiler shell II and the reservoir 41. The conduit59 is connected by a conduit 63 to the boiler shell II and this conduitis controlled by a motorized valve 64. When the valve 64 is open,circulation is permitted through the conduit 22, pump 23 and conduits 59and 63 to agitate cr stir up the fluid contained in the boiler shell II.This is an effective method for agitating the fluid in the boiler shellII to prevent stratification and consequent crystallization of the fluidtherein.

A humidity responsive controller 65 responsive-to therelative humidityof the dehumidiiled air leaving the dehumidifying unit controls thevalve 32 to regulate the amount of hygroscopic fluid of relatively highconcentration delivered to the dehumidifying unit. f

A temperature responsive controller 66 connected by a capillary tube 61-to a bulb 68 located inthe fluid' in the boiler shell II is utilizedfor controlling the operation of the fuel rvalves I6 and 20 to maintaina substantially constant temperature within the boiler shellI` Il. Whenthe Atemperature is low the temperature controller 66 maintains bothlfuelfvalves 20 and I6 open. to provide a high flame for the boiler. Asthe temperature increases the valve 20'is closed to provide a lowflameand if the temperature increases to a predeterminedhigher value thevalve I6 is closed to shut down the burner I3. Preferably thetemperature controller 66 is so adjusted that it will maintain thetemperature of the fluid in the boiler at substantially 215.

A differential temperature controller 10 is connected by a capillarytube 1I to a bulb 12 located in the upper portion of the fluid in theboiler and' is also connected by a capillary tube 13 to a bulb 14located in the lower portion of the boiler. This differentialtemperature controller 19 therefore responds to the temperatures at twopoints in the fluid in the boiler and operates to open the Valve 64 whenthe temperature differential exceeds, say 5. This causes agitation'ofthe fluid inthe boiler and therefore prevents stratification andcrystallization of the fluid in the boiler. Y

A liquid level controller 16 controls the valve 56 and the pump 51 tosupply fluid to the boiler shell vI I from the reservoir 41 upon adecrease in level therein. In other'words, the liquid level controller16 operates to maintain the level of the fluid in the boilersubstantially constant.

A liquid level controller 11 connected to the lower portion of thereservoir 41 controls the valve 60 to admit fluid from the boiler I0 tothe reservoir 41 when the level-of the fluid in the reservoir falls to apredetermined low value. Accordingly, the liquid level controller 11operates to maintain at leastV a Ipredetermined amount of liquid in thereservoir 1'I1.v

Liquid level controller connected to the reservoir 41 in the upper-endthereof operates the valve 45 to close the valve 45, which prevents thesupply of fluid to the reservoir 41 when the level therein reaches apredetermined high value. n other words, the liquid level controller 88operates to shut olf the supply of fluid to the reservoir 41 to preventoverflow therefrom.

If the liquid level in the reservoir approaches the overflow conduit 5I,a liquid level controller 82 sounds an alarm 8| indicating that thelevel in the reservoir 41 is extremely high and that the system is notoperating properly. When this alarm 8| is sounded the engineer on thejob is notified of the fact that the system is not operlating properlyand if he feels that the reservoir 41 may overflow he may place thecontainers 53 under the overflow conduit 5| to catch the fluid in caseit overflows from the reservoir 41.

A second liquid level controller 83 connected to the boiler at a lowerlevel operates to shut oifthe burner I3 and to open the valve 45. Thisprovides a safety control for the boiler to shut oif'the burner when thelevel of the fluid there- 4:in gets too low and to open the valve 45 tosupincrease in pressure differential the differential pressurecontroller 85 will pull in a relay 88 to energize heaters 80 in the heatexchanger 24 to heat up the hygroscopic iluidof relatively highconcentration to prevent vthe crystallization or solidification of theuid in the heat exchanger 24. This is an extremely practical and suremethod of insuring that the' hygroscopic fluid will not crystallize andsolidify in the heat exchanger 24 during the starting up period orduring periods when dehumidifying unit 29 `is shut down. It is foundthat in boilers Yof this type for concentrating a hygroscopic fluid thaton occasions the fluid in the boiler becomes extremely turbulent and inorder to reduce this lturbulence to prevent priming of the boiler, thatis, the ow of fluid out of the boiler, I supply air under pressure tothe surface of the iluid in the boiler. This has a marked effect on theturbulence of the fluid in the boiler. It is found that the applicationof air to the surface of the fluid in the boiler decreases theturbulence thereof to a minimum and acts as a carrier for the steamflowing through the conduit 6| reservoir 41, duct'50 and breech I4 tothe stack, not shown. The air under pressure also has a tendency topierce or break up the bubbles caused by boiling, and the breaking up ofthe bubbles in thisV manner materially decreases the bubbling effect andtherefore materially decreases the turbulence of the fluid. Thissupplying of air is accomplished by means of a pipe 9| leading from somesource of air under pressure, not shown, to a nozzle arrangement 92located in the boiler above the level of the uid therein. The supply ofair through the pipe 9| to the nozzle arrangement 92 may be controlledby a motorized valve S3' which may be graduatingly positioned byaresistance type controller 94 contacted by the fluid in the boiler. Theiluid being a relatively good conductor of electricity will vary theresistance of the resistance type controller 94 which will graduatinglyposition the valve 03 in accordance with the amount of splashing orturbulence of the fluid to maintain the turbulence of the fluid at aminimum. If desired an on and olf type controller as distinguished fromthe modulating or proportioning type illustrated may be utilized to turnon the air supply if the turbulence of the iiuid becomesexcessive. Y

The particular manner in which thefvarious If the iluid coming from theboiler u controls illustrated in Figure lare connected together andoperated is shown in Figure 2.

The temperature "responsive controller 66 is shown to comprise .'abellows '|00 connected by the capillary tube 61 to the bulb 68. The bulb68 contains a volatile fluid sothat the bellows |00 is expanded andcontracted in accordance with variations in temperature affecting thebulb 63. `The bellows |00 operates a pivoted lever I0| against theaction of a tension spring |02 to operate' switches '|03 and |04. -Uponan increase in temperature the switch I 03 is rst opened and then at`a`higher temperature the switch |04 is opened and likewise upon a decreasein temperature the switch |04 is first closed and then the switch |03 isclosed. By adjusting the tension in the springY |02 thetemperaturesetting of th controller 66 may be adjusted at will.

The liquid levelvcontroller v03 may comprise a lever |05 provided with afloat |06 responding to the level Vof the liquid in the boiler shell IThe lever |05 operates a double-ended mercury switch |01. When the levelof the liquid in the boiler shell is normal the two right-handelectrodes are bridged by the mercury 'and the two left-hand electrodesvare vunbridged." When the liquid level in theA boiler shell becomesabnormally low the switch |01 is tilted to the opposite position tounbridge the right-hand elec-v trodes and bridge the left-handelectrodes.

Line wires leading from somesource of power, not shown, are designatedat ||0'and I. Assume now that the level of the fluid in the boiler isnormal and that the temperature thereof is low so as to cause bothswitches |03f and |04 to be closed.l A circuit, is then completed fromthe line wire ||0 through wire ||2, switch |03, wire I3, motorized Valve20 and wire I|4 back to the other line wire Completion of this circuitcauses opening of the `motorized valve^20. At this same time anothercircuit is completed from the line wire I0 through wire ||5, switch |04,wire IIB, switch |01, wire II1, motorized valve I6 and wire ||8 back tothe other line wire |ll.

This circuitopens the 'motorized valve IB. yWith the two valves |6 and20 open, the burner I3 is operating under high flame; Ify now thetemperature of the fluid within the boiler increases so as to move theswitches |03 and |04 to the positions shown in Figure 2, the circuitthrough the motorized valve 20.is broken to close the valve 20. As aresult, the burner I3V is operating on low ame. If the temperature ofthe fluid becomes too high so as to open the switch |04 or if :the levelof the uid inthe boiler shell decreases to an abnormally low value, theswitches ingly, the burner I3 is controlled in accordance with'thetemperature of the fluid in the boiler shell andif the temperatureshould become too high or 'if the level of the fluid therein becomes toolow the burner I3 is shut off.

The differential temperature controller generally designated at 10 maycomprise a bellows |20 connected to the bulb 12 containing a volatileiiuidand a bellows |2| connected to the bulb 14 containinga volatileiiuid. `The bellows |20 and |2| are therefore operated in accordancewith the temperature affecting their respective bulbs. The bellows |20and |2| operate a pivoted lever |22 for operating al mercury switch |24.A

= spring |23 urges -the lever |22V ina clockwise direction so that the.temperature affecting the bulb 1,4 must increasea predetermined amountabove the temperature aiecting the bulb 12 `be- `fore the lever '|22 isrotated in a counter-clockwise direction. For purposes of illustration,it is assumed that when the temperature affecting the bulb 14 becomes 5more than the temperature affecting thebulb' 12 .the spring |23 isovercome to tilt the switch |24 to a closed position. By adjusting thetension'in the spring |23 the differential in temperatures at which theswitch |24 is operated may be adjusted. at will. When the switch |24 ismoved to a closed position as a result of the temperature affecting thebulb 14 being 5 above the temperature .affectingthe bulb 12, a circuitis completed from the line Wire through wire |25, switch |24, wire |26,motorized valve 64 and wire |21 back` to the other limewire Completionof this circuit opens the motorized valve 64 to cause agitation of theuid in the boiler shell in the manner pointed out above. As a result ofthis agitation, the temperature differential isfdecreased and the.switch |24 is moved to the open position as shown in Figure 2 and thevalve 64 is closed. Accordingly, when stratification tends to take placein the boiler |0 so as to cause the temperature at the lower portionthereof to be more than the temperature at'the upper portion thereof,the valve 64 is opened to cause agitation of the fluid in the boiler todecrease to a minimum the stratiiication of the fluid.

The liquid level controller 16 is shown to comprise a pivoted lever |29connected to a float |30 operated in response to variations in level Vofthe iiuid in the boiler shell' ||.Y The lever |29 operates a mercuryswitch |3| so that when the level in the boiler decreases to apredetermined value the switch |3| is closed. When the switch |3| isclosed a circuit is completed from the line wire ||0, through wires |32and |33, switch |3|, wire |34, motorized valve 56 and wires |35 and |36back to the other line wire Completion of this circuit opens themotorized valve 56 to supply fluid from the reservoir 41 to the Vboiler|0 to maintain the level of the fluid in the boiler at a substantiallyconstant value. 'The pump 51 located in the conduit v55 may be connectedin parallel with the motorized valve 56 by wires |31 and |38 so thatwhen the valve |56 is opened the j pump 51 is operated. This insures thesupply of fluid through the boiler shell if the gravity head is notsuiiicient to supply the iiuid.

The liquid level controller 11 may comprise a pivoted lever |40 operatedby a float |4| in response to the level of the uid 'in the reservoir4'1. 'Ihe lever |40 operates a mercury switch |42 to a closed positionwhen the level of the liquid in the reservoir 41 decreases to apredetermined value. Closure of the switch |42 completes a circuit fromthe line wire |I0 through wire |43, switch |42, wire |44, motorizedvalve 60 and wire |45 back to the other line wire Completion of thiscircuit opens the motorized valve to supply fluid from the boiler l0 tothe reservoir 41 to insure that there will always be at least apredetermined amount of fluid in the reservoir 41 for supply to theboiler. 'When the level of the fluid in the reservoir 41 rises to thedesired minimum value the switch |42 is opened and the motorized valve60 is closed to stop the further supply of fluid.

The liquid level responsive controller 80 may comprise a pivoted lever|41 carrying a float |48 responsive to the level of the liquid in thereservet() voir 41. yThe lever|41 carries a mercury switch |49 which isnormally maintained in the position shown in Figure 2 wherein theelectrodes are bridged. With the parts in this position a circuit -iscompleted from the line wire I0 through wires |32, |50, |52 and |53,mercury switch |40, wires |54 and |55, motorized valve 45 and wires |56,|58 and |36 back to the other line wire Completion of this circuitmaintains the motorized valve 45 open so that uid of relatively lowconcentration may be supplied to the reservoir 41. If the level of thefluid in the reservoir41 should become extremely high the switch |49 istilted in a clockwise direction to unbridge the electrodes. Unbridgingof the electrodes interrupts the circuit through the motorized valve 45to close the same and interrupt the supply of -iluid to the reservoir41.

The left-hand electrodes of the mercury switch |01 of the liquid levelcontroller 83 are connected in parallel with the left-hand electrodesofthe mercury switch |49 of the liquid level controller by means ofwires |62 and |63 so that if the electrodes of theY mercury switch |49are unbridged to normally have the valve 45 closed, the left-handelectrodes of the switch |01 of the liquid level controller 83 may openthe valve 45 if the level of the fluid in the boiler |-0 should becomedangerously low. In other words, the liquid level controller 60 mayclose off the valve 45 to prevent the further supply of fluid to thereservoir 41, but if the level of the liquid within the boiler i0 shoulddecrease to a dangerously low value this valve 45 will be opened by theliquid level controller 83 regardless of whether the liquid levelcontroller 80 demands that the valve 45 be closed.

'Ihe differential pressure controller generally designated at maycomprise a bellows |65 connected by a pipe 86 to the conduit 22 and abellows |66V connected by a pipe 81 to the conduit 25. The bellows |65and |66 operate a pivoted lever |61 and a tension spring |68 urges thislever in a counter-clockwise direction. The lever |61 operates a mercuryswitch |69. The spring |68 operates against the bellows |65 so that whenthe pressure affecting the bellows |65 rises a predetermined amountabove the pressure affecting the bellows |66 the mercury switch |69 ismoved .to a closed position. By adjusting the tension in the spring |68the differential pressure setting of the dierential pressure controller85 may be varied at will. The switch |69 controls the relay generallydesignated at 88, and the relay 88 may comprise an operating coil |10for moving a switch arm |11 with respect to a contact |12. When theoperating coil |10 is energized, the switch arm |1| is moved intoengagement with the contact |12 and when it is deenergized the switcharm |1| is moved out of engagement with the contact 12 by means ofsprings, gravity or other means, not shown.

When there is danger of the fluid of relatively high concentrationpassing through the heat exchange 24 crystallizing or solidifying, thedifferential pressure controller closes the switch |69 to complete anenergizing circuit for the relay 88 which may be traced from the linewire ||0, through Wires |32, |50, |13, |14 and |15, switch |69, wire|16, operating coil |10 and wires |11, |18, |19, |58 and |36 back to theother line wire I I. Completion of this circuit energizes the relay 88to move the switch arm |1| into engagement with the contact |12.Movement of the Iswitch arm |1| into engagement with the contact |12completes a circuit from the line wire IIO,. through wires |32, |50,|13, I14 and |80, switch arm I1I, contact |12, wire |8I, heater elements89 connected in parallel, and wires |82, |83, |18, |19, |58 and |36 backto the other line wire III. Completion of this circuit causesenergization of the heater 89 to heat the fluid of a relatively highconcentration passing through the heat exchanger 24 to insure that thefluid will'not crystallize or solidify in the heat exchanger. 24.. Whenthe pressure differential. decreases the switch |69 is opened, the relay88 is dropped out and the heaters 8 9 are deener'gizeds The liquid levelcontroller 82 may comprisefa pivoted lever |90 operated by a iioat |92'for oper ating a switch |93. When the level of the liquid in thereservoir 41 rises-to a value which indicates that the fluid in thereservoir-41 may over? ow through the conduit 5I, the oat |92V rises toclose the mercury switch |93 to complete a circuit from the line wire lII0 through wire |94, mercury switch |93, wire |95, alarm 8| and wire |96back to the other line wire I I. Completion of this circuit operates thealarm 8I'to notify the engineer that the system is not operatingproperly and that there is danger of the fluid in the reservoir 41overflowing.

The Valve 32 which controlsv the supply .o f hygroscopic uid ofrelatively high concentration to thedehumidifying unit-29 may beoperated. by a proportioning motor of v.the type shown and described inPatent No. 2,028,110 granted to D. G. Taylor on January 14, 1936.proportioning motor is provided with'three l.cegmtrol terminals whichare connected to a potentiemeterA resistance 200.and slider .controlledby =the hurnidii'fy'ire-v sponsive'contro1ler,6 5. The humidityresponsive controller may comprise a lever: 2'02 for operating theslider. 20| with respect to the potentiometer resistance 200. The leverV202 isbiased'inone direction by lmeans of a spring203 andis posi-vtioned by a humidity responsive element 204. Power is supplied to the`proportioning motor from the line wires l0 and I I I ,by wires 20,5andl 206. Upon an increase in relative humidity the slider 20| is movedto theright with respectI to the resistance element 200 and the vvalve32 is moved toward an open position in an amount proportional to theamount of movement of the slider 20 l. Upon a decrease Ain relativehumidity the slider 20| is moved to the left and the valve 32 is movedtowards a closed position in proportion to the amount of lefthandmovement of the slider 2'0 I Accordingly, the valve .32 is positioned inaccordance with the relative humidityof the' air leaving thedehumidifying unit 29 toregulate the flow of concentrated hygroscopicuid to the dehumidifying unit to maintain the lrelative humidity of theair leaving the unit ata subtantially constant value. l

-The'valve-93 which regulates the supply of air tothe surface of, theliquid-in the. boiler shell I I .maybe operated by a rackf2|0fwhichin'ltrn operatedbya.v pinion 2| lf. mounted onfashaft 2|2. The shaft 2|2is'opeatedV throughY a'reducf tion geartrain; 2I3 by motor rotors` 2|4and 21I5. The'fmotor lrotorfslf l 4` and A2 I5 vare` provided. withiield windings. 2I6 fand .211 respectively. 'j The field windings 216and 2I.1.are.lcntrol1ed'by`a switch-arm V2`I8 cooperating with` contacts2I9 and220. ff When the switch arm 2| 8 is, moved into ,engagement withthe contact .2| 9 a circuit 'is cdm- .pleted from --the line wire I I0`through wire ,.22 If,

switch'arm 2m, contact2|aw1re 2,22, eid wind;

.mgmt-andres 2?@ bis eine einer. .1.19 wie III.v EnergiZation of thefield winding 2I6 in this manner causes movement of the valve' 93towards an open position. When the switch army 2I8 is moved intoengagement with the contact.

220 a circuit is completed from the line wire I l0,

through wire 22|, switch arm 2|8, contact 220,

wire 224, field winding 2I1 and wire22'3 back to the other line wire I|I. Energization of the. field winding 2I1 inthis manner moves thevalve`93 towards a closed position.` When the switch arm 2|8 is midwaybetween .the contacts 2|9 and 220 as Villustrated in Figure 2, neitherfield winding 216 or 2|1 is energized and therefore the valve `33remains in the vposition at which it is.

Theswitch arm 218 is controlled byan armature 225 which'is operated byrelay coils 226 and 221. When the field winding 226 is more highlylenergized than the field winding 221 the switch arm 2 I8 is moved intoengagement with the contact 2I9 to move the valve 93 towards an openposition and when the ieldwinding 221 is more highly energized than thefield winding `226 the switch arm 2I8 is moved intor engagementr withthe contact 220 to move the valve 93 towards a closed position. When therelay coils 226 and 221 are equally energized the switcharm 2| 8 ismaintained midway between the contacts 2 I 9 and 220 and therefore thevalve 93 remains'stationary. Power may be supplied to the relay coils226 and 221 by means of a step-down transformer 230 having a primary 23|connected across the wires |25 Vand |21 which are in turn connectedacross the line wires IIO and I|| and a secondary 232. v

vThe resistance type controller 94 may comprise a conductor 235 and aresistance element 236. The conductor 235 and the resistance element 23Sare engaged bythe iiuid in the boiler shell I I, and since this fluidconductselectricity quite readily the conductor 235`and resistanceelement v 236 form a variable resistance .the adjustment of whichdepends upon how much of the resistance is engaged by the fluid intheboiler shell. When the fluid becomes turbulent it engages more and more'of the) resistance'236 to in effect decrease the resistance thereof. v

The shaft 2|24 of the motor which `operates the valve 93 operates aslider 238l with respect to a resistance element 239. The slider 238assumes a 'position with respect to the resistance element 239'corresponding to the position of the valve 93.

As the Valve 93 is moved towards an 'open position" the slider 238 ismoved downwardly and as theV valve 93 is moved towardsja closed positionthe slider 238 is moved upwardly.l The relay coil 221 is connectedacross the secondary 232 of the transformer 230 and has located inseries therewith a variable resistance 240. The relay coil 226 is alsoconnected across the secondary 232 and has located in series therewiththe variable resistance 236 of the controller 94 ,and the variableresistancev 2 '39 of the motor operated valve.

VV'With the level of the liquid midway of the resistance 236 of thecontroller 94 and the valve 93 in a mid position, the resistance 240 isso a'djustedthat the energizations ofthe relay coils 2,26 and 221. areequal, whereupon the parts remain Istationary, in the position shown inFigure 2. Assume now that the level of the liquid due to turbulenceLrises, the resistance 236V is .de creased whereupon the relayv coil 2,26becomes more highly energized than ,thef'relay coil 221. This causesmovement of thejvalve 93 towards an open position 'and also' downwardmovement of the slider 238. When the'slider 238 has moved downwardlysufficiently far to increase the resistance in series with the coil 226,the coils 226 and 221 become equally energized and the valve 93 ismaintained in its newly adjusted position. Conversely, upon a loweringof the level due to a decrease in turbulence of the fluid,v theresistance' 236 is increased and the relay coil 221 then becomes morehighly energized than the relay coil '226. This moves the switch arm 2I8into engagement with the contact 220 to move the valve 93 towards aclosed position and to cause upward movement of the slider 238. When theslider 238 has moved suiiiciently far upwardly to causeA theenergization of the relay coils 226 and 221 to become equal, the switcharm 2I8 is moved to the position shown in Figure 2 and the valve 93 ismaintained in its new position. Accordingly, the valve 93 ismodulatingly or graduatingly positioned in direct accordance with theamount 4of 'turbulence of the fluid withinv the boiler shell l I. Bygraduatingly controlling the supply of air underpressure to the surfaceof the level of the liquid` in the boiler shell l'I, in this manner theturbulence of the liquid is maintained at a minimum at all times.

From the above it is seen that a complete control system for a chemicaldehumidifying system is provided to maintain the concentration of thehygroscopic fluid flowing to the dehumidifying unit ata substantiallyconstant value,` and at the same time to insure that the chemicaldehumidifying system operates safely.

Although for purposes of illustration. one form of this invention hasbeen disclosed, other forms thereof may become apparent to those skilledin the art upon reference to this disclosure, and therefore thisinvention is to be limited only by the scope of the appended claims andprior art.

I claim as my invention:

l. In a system utilizing a solution, the combination of, a boiler forheating the solution to increase' the concentration thereof, a firstconduit for conducting solution` of' relatively high concentration fromthe boiler to a point of use, a reservoir for the solution, a secondconduitr for conducting solution oi' relatively low concentration to thereservoir, a third conduit for conducting the solution from thereservoir to the boiler. heat exchanger means for causing counterow heatexchange between the solution passing through the rst and secondconduitsl heating means for said heat exchanger means, and meansresponsive to the pressure diiferential of the solution of relativelyhigh concentration ilowing through said heat exchanger `means forcontrolling said heating means. 2. In a system utilizing a solution, thecombination of, a boiler for heating the solution to increase theconcentration thereof, a rst conduit for conducting solution` ofrelatively high 'concentration from the boiler to a point of use, areservoir for the solution,v a second conduit for conducting solution ofrelatively low concentration to the reservoir, athird conduit forconducting the solution from thel reservoir to the boiler, a pump forforcing solution `through said Vthird conduit,r a fourth conduit 'forconducting solution from the boiler to the reservoir, andV meansresponsive to` thelevel of the solution in the reservoir for controllingthe iiow of solution through the fburth'conduit.'

I 3.V In a systemyutilizing "a solution,l the combination oi,"a boiler'f 'or heating, 'the solutionfto 'increase the concentration thereof,anrst conduit` for conducting solution of relatively high concentrationfrom the boiler to a point'of use, a reservoir for-the solution, asecond conduit for conducting solution of relatively low concentrationto the reservoir, a thirdA conduit for con-2 ductingr the solution fromthe reservoir to the' boiler, a pump for forcing'solution throughsaidthird conduit, a fourth conduit for conductingsolution from the boilerto` ,theV reservoir,imeans responsive to a low solution level in thevreservoir for causing flow of solution through the. fourth conduit, andmeans, responsive to aL high solution level in the reservoirL fordecreasing the flow of solution through the second conduit.: 1 K 4'. Inasystem utilizing a solution, the combinationof', a boiler for heating'the solution to' increase the concentration thereof, a first conduit forconducting solution of relatively high concentration from vthe boiler toa point of use; a reservoir for the solution, a second conduit forconducting solution of relatively low concentra` tion to the reservoin,a third conduit for conducting the solution from the reservoir to theboiler, and meansresponsive to the level. of the solution in the boilerfor controlling-,the flow ofv solution through the third conduit formaintaining saidlevel at a substantially constant value, meansresponsive to the level of the solution in the reservoir for decreasingthe flow through the second conduit when said level reaches apredetermined high value, andA means responsive to a low level ofsolutionkin the boiler for increasing the ilow through the secondconduit independently of said first named means.

5,.,In a. system utilizing a solution, the combination of, a` boiler forheating the solution'to increase thel concentration thereof, a firstconduit for conducting solution of relatively high concentrationv fromthe boilerA to a point of use, a reservoir' for the solution, a secondconduit for conducting solution of relatively low concentration to thereservoir, a third conduit for conducting the solution from thereservoir to the boiler, means responsive to the level' of: the solutionin .the reservoir forV decreasing the now through the second conduitwhen said level reaches a predetermined high value, and means responsiveto a low level of solution in the boiler for increasing the ow throughthe second conduit independently of said first named means.

6. 'In a system utilizing a solution, the combination of, a boiler forheating the solution to increase the concentration thereof, a firstconduit for. Vconducting solution of relatively hignconcentration. fromthe boiler to a.v point of use, a reservoir for the solution, a secondconduit for conducting solution of relatively low concentration to thereservoirl a third conduit' for conducting the solution from thereservoir to the boiler, firing means for the boiler, means responsiveto the temperature ofthe solutionl inthe boiler for controllingk thefiring means, andy means responsive to apredetermined lowllevel of thesolution'in the boiler' for deenergizing ,the tiring '7'.` In a systemutilizing asoluti'onythe" combination of` agboiler iorheating the4solution; to increase. the Vconcentration, thereof', a filrst 4conduitfor conducting Ysolution, of relatively high concentration' from theboilerto a point, off-use, a reservoir' for the solution, a secondconduit for conducting solution of relatively lowconcentrationl to. the.reservoir, a third conduitv lfor conductingfthe solution fromthereservoir tothe boiler, firing means for the boiler, means responsiveto a predetermined low level of the solution in the boiler fordeenergizing the iiring means, means responsive to a predetermined highlevel of the solution in the reservoir for decreasing the now throughthe second conduit, and means responsive to a predetermined loW level ofthe solution in the boiler for increasing the ow through the secondconduit independently of the level of the solution in the reservoir.

8. In a system utilizing a solution, the combination oi, a boiler forheating the solution to increase the concentration thereof, a rstconduit for conducting solution of relatively high concentration fromthe boiler to a point of use, a reservoir for the solution, a secondconduit for conducting solution of relatively low concentration to thereservoir, a third conduit for conducting the solution from thereservoir to the boiler, ring means for the boiler, means responsive toa predetermined low level of the solution in the boiler for deenergizingthe ring means, means responsive `to a predetermined high level of thesolution in the reservoir for decreasing the flow through the secondconduit, means responsive to a predetermined low level of the solutionin the y boiler for increasing the oW through the second conduitindependently of the level of the solution in the reservoir, and meansresponsive to the temperature of the solution in the boiler forcontrolling the firing means to maintain a substantially constanttemperature thereof.

9. In a system utilizing a solution, the combination of, a boiler forheating the solution to increase the concentration thereof, a rstconduit for conducting solution .of relatively high concentration fromthe boiler to a point of use, a reservoir for the solution, a secondconduit for conducting solution of relatively low concentration to thereservoir, a third conduit for conducting the solution from thereservoir to the boiler, ring means for the boiler, means responsive toa predetermined low level of the solution in the boiler for deenergizingthe firing means, and means responsive to the level of the solution inthe boiler for controlling the flow of solution through the thirdconduit to maintain said level at a substantially constant value.

10. In a system utilizing a solution, the combination of, a boiler forheating the solution to increase the concentration thereof, a first conrduit for conducting solution of relatively high concentration from theboiler to a point of use, a reservoir for the solution, a second conduitfor conducting solution of relatively low concentration to thereservoir, a third conduit for conducting the solution from thereservoir to the boiler, iiring means for the boiler, means respon--sive to a predetermined low level of the solution in the boiler fordeenergizing the-firing means, means responsive to the level of thesolution in the boiler for controlling the flow of solution through thethird conduit to maintain said level at a substantially constant value,and means responsive to the temperature of the solution in the boilerfor also controlling the firing means to maintain said temperature at asubstantially constant value. p

11. In a system utilizing a solution, the combination of, a boiler forheating the solution to increase the concentration thereof, a rstconduit for conducting solution of relatively high concentration fromthe boiler to a point of use, a reservoir for the solution, a secondconduit for conducting solution of relatively low concentration to thereservoir, a third conduit for conducting the solution from thereservoir to the boiler, and a fourth conduit for conducting steam andentrained solution from said boiler to said reservoir where saidsolution may be separated from the steam and may return to said boiler;`

12. In a system utilizing a solution, the combination of, a boiler forheating the solution to increase the concentration thereof, a rstconduit for conducting solution of relatively high concentration fromthe boiler to a point of use, a reservoir for the solution, a secondconduit for conducting solution of relatively low concentration to thereservoir, a third conduit for conducting the solution from thereservoir to the boiler, a fourth conduit for conducting steam andentrained solution from said boiler to said reservoir where saidsolution may be separated from the steam and may return to said boiler,a combustion chamber adapted to contain a re for heating the solution insaid boiler, a iiue for conducting the products of 4.combustion to theatmosphere, and a iifth conduit for conducting steam from said reservoirto said iiue.

13. In a. system utilizing a solution, the combination of, a boiler forheating the solution to increase the concentration thereof, a rstconduit for conducting solution of relatively high concentration fromthe boiler to a point of use,

a heat exchanger means for cooling the solution passing through saidconduit, heating means for said heat exchange means, and meansresponsive to the pressure differential of the solution of relativelyhigh concentration iiowing through said heat exchanger means forcontrolling said heating means.

ROBERT B. P. CRAWFORD.

